Colonoscopy

What is a colonoscopy?

A colonoscopy is an investigative procedure that allows us to see inside your colon (large bowel) without making incisions. Performing a colonoscopy means we can see inside your colon and its inner lining, and we can perform the procedure in both adults and children.

We use a unique tool called a colonoscope during this procedure. A colonoscope is a thin, flexible tube with a video camera on one end that relays images back to a screen in the room. The colonoscope is inserted into your bottom and gently moved up into your colon so we can assess its inner lining.  

Our specialists in digestive health lead private gastroenterology services at St Thomas’ and Evelina London Children’s hospitals, so when you choose us, you can be confident that you’re in safe hands.

Who is a colonoscopy for? 

We perform colonoscopies in adults and children experiencing distressing bowel symptoms.  

A colonoscopy may be advisable if you develop new bowel symptoms that do not have an obvious cause.  

Having a colonoscopy ensures you receive an accurate diagnosis of your symptoms. Some bowel conditions also benefit from early detection and treatment.  

We can use a colonoscopy to screen people at high risk of developing bowel cancer, such as those with previous colonic polyps, or those with a family history of polyps or bowel cancer. 

What does a colonoscopy show? 

A colonoscopy can highlight many issues with your large bowel (colon), and we usually recommend colonoscopies to investigate the causes of symptoms affecting these parts of your body.  

Symptoms that may require a colonoscopy to investigate include:  

• bleeding from your bottom 
• blood in your poo 
• chronic diarrhoea or constipation 
• unexplained weight loss 

We can also use a colonoscopy to check polyps in the bowel. A polyp is a growth that is generally harmless. However, there is a risk that they can turn into bowel cancer so if we find a polyp, it must be removed. 

Our specialist can take a biopsy (tissue sample) of the polyp during your colonoscopy to look for inflammation or infections. In most cases, we’ll remove the polyp completely during the procedure. 

Another role colonoscopies play is in diagnosing bowel conditions, such as:  

• bowel cancer 
• Crohn’s disease 
• diverticular disease  
• diverticulitis 
• haemorrhoids 
• ulcerative colitis  

Sometimes, you may need further testing alongside your colonoscopy to confirm a diagnosis.  

For personalised advice on whether a colonoscopy is right for you, make an online enquiry to our gastroenterology team.

How to prepare for your colonoscopy

Colonoscopy preparation is essential as it determines whether we can perform the procedure on the scheduled day.  

Colonoscopy preparation can include:  

• drinking a special laxative (medicine that makes you poo) before your appointment to empty your bowels completely 
• fasting for several hours before your procedure 

In the days leading up to your colonoscopy, you’ll need to adjust your diet and only eat plain foods like chicken, white bread, pasta, rice and clear broth. Our team will give you detailed dietary information in advance.  

The day before your colonoscopy, you must drink sachets of laxatives throughout the day to empty your bowels. Clearing the bowels of food and poo will improve the clarity of colonoscope images. Try to stay at home and near the toilet once you start drinking the laxatives.  

On the day of the colonoscopy, you should not eat or drink. We’ll tell you exactly when you need to stop consuming anything.  

When we set the date for your colonoscopy, we’ll provide you with all the necessary preparation information to ensure you’re well-informed and ready for your procedure. 

If you are considering a colonoscopy, complete our online enquiry form to arrange an appointment with one of our specialists.

How is a colonoscopy performed? 

On the day of your appointment, we’ll talk you through what will happen. A colonoscopy is usually performed under sedation. 

Once we have your consent to proceed, we’ll begin your colonoscopy. First, we’ll insert the colonoscope into your bottom. The action shouldn’t hurt, but it can feel slightly uncomfortable. Next, we’ll pump additional air into your bowels to help open them up. The air can cause you to feel bloated or like you need to go to the toilet.  

The colonoscope will be passed through to your colon and you might feel some cramping. Once it’s in place, we’ll assess your colon.  

We’ll remove and perform biopsies on any polyps. You won’t feel this happening. Once your doctor is happy that they’ve assessed your colon, they will gently remove the colonoscope and you will be taken to the recovery room.  

It’s important that you arrange for someone to take you home after the procedure as you will be unable to drive following the procedure.

Children’s colonoscopy 

On the day of your child’s colonoscopy, we’ll make sure they’re well enough to have it. We perform colonoscopies in children under general anaesthetic, so they’ll be asleep throughout. It stops them from feeling any discomfort or moving during the procedure.  

Once the colonoscopy is complete, we’ll take them to the recovery room, where they’ll wake up and you can come and see them.  

Our children’s gastroenterology services prioritise your child’s safety at all times. We want parents to trust us as their child’s healthcare provider and feel secure knowing that their child is in good hands.

How long does a colonoscopy take?

A colonoscopy typically takes between 30 and 45 minutes to complete. However, you may be in the hospital for around 2 hours from start to finish.

Are there any side effects of a colonoscopy? 

A colonoscopy is considered a safe procedure but there are some possible side effects.  

After your colonoscopy, you might:  

• bleed a little bit from your bottom 
• feel bloated  
• have a small amount of blood in your poo 
• have stomach cramps 

These side effects are common and not a cause for concern. However, seek medical attention if:  

• you have a fever 
• you have severe, worsening stomach pain 
• you’re bleeding heavily from your bottom or it’s getting worse

Helping your child recover at home 

After your child has had their colonoscopy, we’ll explain how you can support their recovery. Encourage your child to drink fluids and help them to feel as comfortable as possible.  

They’ll likely need the day off school to fully recover at home before returning to normal activities. Your child may feel bloated or have stomach cramps. Passing wind may help alleviate this.  

If you have questions about the procedure or recovery, complete our online enquiry form to speak to our team.

Colonoscopy results

You won’t receive your colonoscopy results on the day of your appointment because we must assess the images and create a comprehensive report of the findings.  

Normal results with no polyps, signs of cancer or other digestive conditions mean you may need further tests to confirm the cause of your symptoms.  

If a polyp is removed or biopsies are taken, they will be sent to the laboratory for analysis. The results will be sent to you in 7-10 days. 

Should your results confirm a bowel condition, we’ll explain your next steps. You may require further tests and a personalised treatment or management plan to help minimise your symptoms.  

Book a colonoscopy with expert care

If you are experiencing symptoms or would like reassurance, our experienced gastroenterology consultants are here to help. We offer fast access to colonoscopy, accurate diagnosis and personalised care to support your digestive health.

Complete our online enquiry form to request an appointment and speak to a specialist.